Process for plugging back or bridging wells



Spi.. 117, i935. E. P. HALUBURTON 2?@49563 PROCESS FOR PLUGGING BACK OR BRIDGING WELLS Filed April 1o, 1934 Z o@ U M 7/.. N 6 Mu UME; T Ik, 2 j

Patented Sept.. 17,* 1935 NiJNlrizu STATES PATENT oriuci:l

PROCESS FOR PLUGGING BACK OR BRIDGING WELLS Erle P. Halliburton,

Los Angeles, Calif., assignor to Halliburton Oil Well Cementing Company, Duncan, Okla., a corporation of Delaware Application April 10, 1934, Serial No. 719,883

6 Claims. (Cl. 166-21) it desirable to plug a well-hole at some desiredv point to shut olf the formations below from the formations above.

Heretofore, when an oil driller has attempted to plug off or bridge the bottom of a well-hole, the operation has been accompanied by danger of sticking a pipe in the well-hole. The general practice has been to insert into the well a casing or tubing leading to near the bottom of the well. The uid cement is then pumped through the tubing or casing to a height somewhat above the point where the well is to be shut olf or plugged, and the casing has then been elevated to the desired shut-off point, whereupon the excess -cement has been removed from the wellhole by circulating mud down the casing or tubing to wash out such excess cement. Quite frequently, it is found that the casing or tubing has been frozen at the bottom of the Well-hole by the cement'vvhenV it is desired to elevate the Same.

by the provision at the end of the tubing of a special plug back device or section' of tubing detachable from the remainder of the tubing, so that it may be intentionally left in the bottom of the well-hole afterthe plugging back or bridging operations. By constructing such plug back device or section of tubing of such material that it may be readily drilled from the Well-hole, the

4plugging back operation will not interfere with future deepening of the well-hole, in case such operations are later found desirable.

The present invention further comprehends that the process of plugging back the oil Well may be more readily and certainly accomplished if in the process and apparatus provision is made for circulation of mud fluid at the desired shutoff point without disconnecting the tubing from 5 the lower section or' plug back device, and for this purpose the present process and apparatus makes special provision for such circulation.

A further feature of the present process and apparatus is the use of plugs, and cooperating 10ft' apparatus for catching or arresting the plugs at desired points by which the position to which the cement is forced in the operationsis automatically determined so that it becomes unnecessary to judge when the cement is in the desired po- 15 sition by measuring the amountfof fluid introduced into the well-hole. In the usual practice of plugging back or bridgingfjav well-hole, the operator has to measure the amount of il id fintroduced in the well-hole in rder to' est ate' 20 when the cement has been passed to the desired point. This measuringoperation is accompanied by frequent errors, Aand as a--result the well is, frequently bridged ',.orl ,shut ffoff at the wrong point. l

Various further advantages and features of the y present invention will be apparent from al-@def scription of a preferredform or example of,` a process and apparatusembodying the invention'. For this purpose, one form or example of such a process and apparatus is hereafter described with reference to the accompanying drawing, in which,-'

Figure 1 is a sectional View of an oil well with anl apparatus installed therein illustrating the position of the apparatus and the stage of the process during the operation of pumping the cement into the well-hole;

Figure 2 is a similar view of the apparatus showing the position at the stage of the process after the cement has reached the desired position and the apparatus is in Iposition for washing out the excess cement;

Figure 3-is an enlarged vertical section of the plug back device;` and Figure 4 is an enlarged vertical section of the releasing device and slide valve member, preferably included in the process vand apparatus.

l Referring to the drawing; the apparatus comprises a string of pipe or casing I, which may be built of sections in any usual or preferred manner. The lower end of the string of pipe I is attached to a releasing device and slide valve memv ber 2. The releasing device and slide valve member 2, in turn, is detachably connected with the plug back device 3.

Now, referring more particularly to Fig. 3, the plug back device 3 may be any form of tubing provided with a suitable means, such as a J-slot 4, for readily detaching the same from the releasing member 2. In place, for example, of the J- slot connection, such as indicated at 4, other suitable connection means, such as a left-hand thread, may be employed. The plug back device is shown as including a back pressure valve 5 at near its upper end and with the distributing nozzle ISEL at its lower end. The plug back device should be constructed of a material or materials which can be readily drilled out of the bottom of the well-hole, if later it should be desired to again drill out the bottom of the well-hole.

The preferred form of the plug back device illustrated comprises the upper collar E, which contains the J-slot 4 and is provided with a. seat 1 for the back-pressure valve 5. This collar, in turn, is threaded to a nipple 8, which is indicated as having a reduced portion 9, which in its lower end connects with a thin sleeve I0. The lower end of the sleeve I0 connects with a nipple I I similar to the nipple 8, which'in turn, is threaded to the nozzle 6, which is preferably provided with a lower discharge port I2 and a plurality of equally spaced apart lateral discharge ports I3.

Between the nipples II and 8 is the body of the plug back device, which may in practice be of various lengths, depending upon the distance that the oil well is to be plugged back in operation. In order to construct the device so that it may be most easily drilled out of the well-hole. a body of the device between the nipples 8 and II is formed of hardened cement or concrete I4, which may be suitably strengthened by a reinforcing screen I5, if desired. The other portions of the plug back device, such as the collar 6, nipples 8 and II, and distributing nozzle I58L should'be formed of a material easy to drill, such as aluminum or easily fractured cast iron.

The releasing and slide valve member 2 (Fig.' 4) comprises a tube I6, preferably provided near its lower end with a cross-pin I1 adapted to enter J-slot 4 of the plug back device 3 for attaching such plug back device to the tubing I. The upper end of the releasing device 2 is provided with a threaded socket I8 or other suitable means for attaching the same to the body of tubing I. The process and apparatus may, if desired, rely upon detaching the plug back device from the tubing for the operation of washing out the excess cement, but preferably this releasing member 2 is made to include a slide valve. For this purpose, the tube I6 is provided with one or more lateral ports I9 normally closed by a sleeve 20 telescoped within tubing I6. This sleeve 20 at its lower end rests upon pins 2| which are constructed of a material readily sheared, so that in operation by shearing the pins 2l the sleeve 20 may be lowered to operate as a valve and uncover the ports or port I9. The sleeve 20 is preferably provided near its lower end with a restricted member 22 for the purpose of catching and holding plugs in the manner hereafter described.

The apparatus also preferably includes a lower plug 23 (Fig. l) and an upper plug 24. 'I'he lower plug 23 may be composed of a material, such as rubber, and is provided with a diaphragm 25 which under pressure is adapted to blow out for the purposes hereinafter described. The upper plug 24 may be any usual customary ferm of plug for cementing purposes.

The process of plugging back or bridging wells in accordance with the present invention as carried out with the use of such apparatus is as follows:

The tubing I is attached to the releasing mem- 5 ber 2 which, in turn, is attached to the plug back" device 3, and the assembled apparatus then lowered into a well-hole, such as indicated at 26, until the top of .the plug back device 3 is at substantially the point at which it is desired 10 to bridge or plug back the well-hole. Circulating fluid, such as mud, is then introduced into the apparatus, as indicated at 21, and circulated down theapparatus to return up and around the apparatus to the top of the well-hole in order to l5 insure that the bottom of the well-hole is free. There is then introduced the plug 23, the purpose of which is to keep the cement separated from the circulating fluid until this cement has been pumped down into the well-hole. After the in- 20 troduction of the plug 23, fresh fluid and unset cement is introduced into the apparatus above the plug 23 in sufficient quantities to fill the bottom of the well-hole up to the desired bridging or plugging off point. In practical operation, it 25 is found always necessary to introduce an excess amount of cement, as the exact requirements for plugging off the bottom of the well cannot be determined. When the desired amount of cement 28 has been introduced, there is then in- 30 serted the upper plug 24, the purpose of which is to protect the cement from contamination with the fluid later to be inserted above the plug 24. Circulating fluid, such as mud, is then inu troduced into the apparatus, as indicated at 29, 30 by means of a pump and by continued pumping the cement is forced down the apparatus.

The plug 23 descends until it encounters the restriction member 22. It is held from further descent by this member and the force of the 40 pump introducing the circulating fluid 29 is sufficient to burst the diaphragm 25 of this plug and the cement 28 then passes downwardly through the plug back device out of the distributing nozzle 6 and rises again-around the 45 apparatus. The upper plug 24, in turn, descends until it strikes the lower plug` 23, after which the continued pump pressure causes the pins 2| to shear which are holding the sleeve valve 20 closed. The sleeve valve 20 then de- 50 scends until it strikes the pin I1, opening the slide valve ports I9. This checks the descent of the cement, which then remains in the apparatus from the pin I1 through the plug back device and up around the plug backy device to a 55 height somewhat above the ports I9. By further pumping down the tubing I, the circulating fluid or mud is caused to pass out of the ports I9 and rise up around the tubing I, carrying to the surface of the Well the excess cement. In 60 certain cases, it may be desirable at this point to reverse the circulation forcing fluid mud down the outside of the pipe I and cause the excess cement to be forced up inside of the pipe. After the excess cement has been removed from the 05 well-hole, the plug back device is detached from the tubing I by lowering and turning tubing I to disengage the pin I1 from the J-slot 4. Leaving the plug back device in the well-hole, the remainder of the apparatus is then With- 70 drawn to the top of the well. The back-pressure valve 5 operates to prevent the cement at the bottom of the well-hole from flowing out of the plug back device.

While the particular form of the process and 75 detaching the detachable lower apparatus herein describedis well adapted to carry out the objects of the present invention, various modications and changes may be made without departing from the principles of the invention, and this invention includes all such modications and changes as come within the y scope of the appended claims.

I claim:

l. A process of plugging a well, which comprises lowering a string of pipe into a well-hole until its lower end is below the point at which the well hole is to be plugged oi, forcing unset cement down the string of pipe in suiicient quantity to more than occupy the space in the well-hole to the plug-01T point, circulating fluid down the pipe and into the well-hole above the plug-off point to remove the excess cement, detaching that portion of the pipe below the plugoi point, and removing the remaining pipe from the Well-hole.

, 2. A process of plugging a well, comprising lowering a string of pipe into the well-hole, having at its lower end a detachable section comvposed of drillable material, the pipe being lowered to bring the detaching point at the height 01T, forcing cement down the string of pipe in suficient quantities to fill the well-hole to above the detaching point, circulating uid above the detaching point to remove the excess cement, detaching the lower section of the pipe, and removing the remaining pipe from the well-hole.

3. A process of plugging a Well, lowering a string of pipe into a detachable lower section composed material and a slide valve thereabove, the pipe being lowered to bring the detachable lower section at the point where the well is to be plugged oil", introducing cement into the well-hole of the pipe until cement lrises outside of the pipe to above the point where the lwell is to be plugged off, opening the valve and then circulating uid through such valve to remove the excess cement, section of the drillable material, then pipe, and removing the remaining pipe from the well-hole.

4. A process of plugging off a well-hole, comprising lowering into the well-hole a string of pipe having a detachable lower section composed of readily drillable material and having thereabove a plug actuated slide valve, intro-y ducing cement into the well-hole through the string of pipe, inserting the vplug in the pipe above the cement and pumping cement downwardly by the use of circulating the i'luid introduced above the plug until the plug is caused to operate in the side valve, then continuing the pump operations to cause a circulation of the circulating iluid to remove any excess cement introduced into the well-hole.

5. A process of plugging a well-hole, comprising lowering a string of pipe into the well-hole, with a. detachable lower section composed of establishing circulation in the well-hole through the string of pipe, inserting in the pipe a plug having a blow-out diaphragm, introducing into the pipe above said plug sucient uid cement for plugging oi the well to the desired. height, inserting a second plug above said cement, and then forcing into the pipe drilling iluid to force said cement down the well-hole, then circulating fluid `to remove excess cement, detaching the lower section of pipe, and removing the remaining Ipipe from the well-hole.

6. A process of plugging a well-hole, which process comprises lowering the string vof pipe into a well-hole, having a detachable lower section equipped with a back-pressure valve, introducing cement into the well-hole through the string of pipe until the same occupies a space within and outside of the detachable lower section of pipe, circulating fluid ab'ove such detachable section to remove excess cement, disconnecting the remaining pipe from the detachable section, and removing the same from the well-hole.

ERLE P. HALLJBURTON. 

